Camera calibration device and camera calibration system

Abstract

The present invention provides a camera calibration device and a camera calibration system with which it is possible to execute calibration even in a situation where the load-bearing state of a vehicle changes, and also to precisely estimate all of camera parameters and execute calibration without utilizing the parallelism of the vehicle to, e.g., a white line. The orientation of a vehicle is estimated on the basis of a prescribed feature amount extracted from a video, the translation-direction position of a camera relative to ground is corrected on the basis of information obtained from the calibration executed at a time in the past such as the time of product shipment, and a camera parameter pertaining to the orientation of the camera relative to ground is calculated on the basis of the orientation of the vehicle and the translation-direction position of the camera relative to ground.

The invention claimed is: 
     
       1. A camera calibration device that is mounted in a vehicle and executes calibration at a time of usage on a plurality of cameras attached around the vehicle and capturing an ambient environment of the vehicle, comprising:
 a processor configured to:
 acquire a video captured by a camera of the plurality of cameras; 
 extract a predetermined feature quantity from the video; 
 estimate a vehicle posture of the vehicle on the basis of the predetermined feature quantity; 
 correct a position in a translation direction of the camera with respect to a ground surface; and 
 calculate a camera parameter related to a camera posture of the camera with respect to the ground surface based on the vehicle posture of the vehicle and a position of the camera in the translation direction with respect to the ground surface, and 
 wherein the calibration at the time of usage further comprising the processor configured to:
 select a reference camera from the plurality of cameras attached around the vehicle; and 
 correct a position of each camera of the plurality of cameras in the translation direction with respect to the ground surface based on a position of the selected reference camera in the translation direction with respect to the ground surface and the vehicle posture of the vehicle, wherein the position of the selected reference camera is obtained from a past calibration executed in the past and stored in a memory in the vehicle, 
 
 wherein estimating the vehicle posture during the calibration at the time of usage further comprising the processor configured to:
 estimate a pitch angle of the vehicle on the basis of the predetermined feature quantity; and 
 estimate a roll angle, a height, and a rotation center of the vehicle on the basis of the predetermined feature quantity, and 
 
 wherein the processor is further configured to:
 extract a linear feature quantity having a straight line shape from the video, and 
 estimate the vehicle posture of the vehicle on the basis of a parallelism of linear feature quantities in parallel to each other in the vicinity of the vehicle in the video and a deviation amount in a boundary between the videos captured by the cameras in a synthesized video generated from the videos. 
 
 
 
     
     
       2. The camera calibration device according to  claim 1 ,
 wherein the processor is further configured to determine whether the calibration is executed. 
 
     
     
       3. The camera calibration device according to  claim 2 ,
 wherein the processor is further configured to: 
 determine whether the calibration is executed on the basis of the parallelism of linear feature quantities in parallel to each other in the vicinity of the vehicle in the video and the deviation amount in a boundary of the videos captured by the cameras in a synthesis video generated from the videos. 
 
     
     
       4. The camera calibration device according to  claim 1 ,
 wherein the processor is further configured to determine whether the vehicle is in a normal running state on the basis of at least one selected from a speed, a steering angle, and a yaw rate of the vehicle. 
 
     
     
       5. The camera calibration device according to  claim 1 ,
 wherein the processor is further configured to determine whether a feature quantity available in the calibration is shown in the video. 
 
     
     
       6. The camera calibration device according to  claim 5 ,
 wherein the processor is further configured to determine whether a feature quantity available in the calibration is shown in the video on the basis of a linear feature quantity of a straight line shape extracted from the video. 
 
     
     
       7. The camera calibration device according to  claim 1 , further comprising a data accumulation storage that accumulates the predetermined feature quantity, and wherein the processor is further configured to determine whether the data accumulation in the data accumulation unit storage is completed. 
     
     
       8. The camera calibration device according to  claim 7 , wherein the processor is further configured to:
 determine whether the data accumulation is completed on the basis of a position where the linear feature quantity is shown in the video. 
 
     
     
       9. The camera calibration device according to  claim 7 ,
 wherein the processor is further configured to estimate the vehicle posture of the vehicle on the basis of the predetermined feature quantity accumulated in the data accumulation storage. 
 
     
     
       10. A camera calibration system comprising:
 the camera calibration device according to  claim 1 ; 
 the plurality of cameras that are mounted in the vehicle such that the captured videos are partially overlapped or adjacent; 
 a synthesized video generation device comprising a processor configured to correct the videos captured by the plurality of cameras using camera parameters of the cameras obtained from the camera calibration device so as to generate a synthesized video; and 
 a display device that displays the synthesized video.